Spark-plug



H. SCHWETGER. SPARK PLUG.

APPLICATION FILED MN. 3. 192D. l 1,368,358. Patented Feb. 15, 1921 FIERE-RENNEN HENRY SCHWETGEE, 0F ROSA1 NEBRASKA.

SPARX-PLUG.

Specilcation of Letters Patent.

Patented Feb. 15, 1921.

ppiicauon ined January 3, i920. seriai No. 349,267.

To all 11i/omit may concern:

lie. it known that I. HENRY SoiiwE'ronu, a citizen of the United States, residing at llora, iu the county of Lancaster and State4 of 'Nebraskiu have invented certain new and useful Improvements in Spark-Plugs;

aud I do hereby declare the following to be a full, clear, and exact descriptioii-ot` the invention, such as will enable others skilled in the art to which it appertains to make and use the saine. i

This invention relates to new and useful improvements in sparli plugs and has for one of its objects the provision of a device oi' this character wherein the spark producing parts are so arranged aud associated with each other as to prevent the accumu lation of carbon and other foreign matterl thereon, thus obviating short circuiting of the device.

Another object of this invention is the provision of a sectional insulator so fitted together and to the body as to prevent the compression of au engine from leaking between the` insulator and body and also provides parts that are not susceptible to be broken and when assembled will entirely ohviate any danger of short cireuiting of the renti-al electrode to the body.

still further object of this invention is the provision ot a. spark plug of the above stated character, which shall he simple` durable and elii'cient, and which may be mamifzwtured and sold at a comparatively loiv cost- With these and other objects in view as will become more apparent as the description proceeds` the invention consists in certain novel features of construction1 combination` and arrangement'of parts as will be hereinafter more fully described and claimed.

For a complete understanding of my invention reference is to be had to the following description, and accompanyingr drawing. in which:-

Figure 1 is a side elevation of aspark plug constructed in accordance with my invention,

Fig. 2 is a vertical sectional View of the spark plug llustrating the spark producing parts associ: ted with each other` Fig. 3 is a detail view of the central electrode.

Referring iii detail to the drawing', the numeral l indicates a body having formed thereon the screw threaded extension :a that is adapted to be threaded into the spark plug opening of an'engiue and the upper portion of the-body is provided with the usual wrench engaging faces 3. The body l is provided with abore 4 having its upper end reduced to form a restricted boro 5 and also an annular shoulder G. The annular shoulder 6 is between the bore 4 andthe restricted bore 5. An' insulator 7 lits ti htly within the bore 4 of the body .1 an formed thereon an extension 8 that is disposed within the bore 5 and projects above the body 1. the insulator 7 defines an annular shoulder 9 that abuts the annular shoulder 6 of the body l, and a washer 10 is a'dapted to be interposed between said shoulders for the purpose of establishing a leak-proof connection between the insulator and the body. The lower portion of the insulator 7 is reduced as illustrated at .11 and has its end rounded as illustrated at 12. The reduced portion 11 delines an annular shoulder 13 adapted to have positioned thereon a Washer 14. 'The insulator 7 has a bore 15 extending throughout its entire length and the lower end of said hors terminates in an enlarged recess 16 that opens outwardly through the rounded end 12 of the reduced end 11 of said insulator 7. A central electrode 17 extends through the bore 15 and has a head 18 of annular formation formed upon its lower end and located within the recess 16. The top face of the head 18 is eut away as illustrated at 19 to define an annular shoulder 20 which shoulder fits within a recess 21 of a corresponding shape and which is formed within the'bottom wall of the enlarged reeesslV 16 of the bore 15. A. washer 22 is interpoed between the head 18 and the bottom wall of the recess 16 to establish a leak-proof connection between the head and the insulator 7. The washers heretofore described are preferably Xeonstructed from asbestos or may be made from any material siiitable-forthe purpose.

From the foregoing description and with reference to the drawing, it will be noted that the lower portion of the head 18 is of considerable thickness so. as to provide a.'

very substantial firing terminal to the central electrode 15. thereby obviating the danger of the burning out of the electrode during the use of the device.

has

The extension 8 formed upon '70 A retaining cap 25 that forms an outer y l relectrode includes a body 26 that has formed ereoa u screw threaded extension 27 threaded into' the lower end of the body 1 between the same and the reduced end 11 et' the insulator 7 and abuts the washer 14 ou the annular shoulder I3 of said insulator 7. The extension "27 defines an annular shoulder 28 to .the body 26 of the cap 25 ano which overlies the end of said body. The body 26 is rounded and provided with an Opening 29 that alines with the recess 16 and has formed thereon an annular flange geonlned within the recess 16 and which flange is cut-away to define teeth 31 that provide electrodes which are spaced from the head 18 to provide spark gaps. .The electrical current is adapted to jump from the head 18 to the .teeth of the cap 25 providing a. series of sparks within the recess 16 ignitin the fuel Within the engine and as the exp osion takes place in the engine, it has a. tendency to remove any particles of forel n matter or carbon from the teeth 3l and t xe head 18.

The upper end4 of the body l is recessed to form an annular seat 32 and also define an annular shoulder 34 to said body for the purpose of receiving an annular extension 35 formed upon a dome-shaped insulator 3G that overlies and closes the upper end of the Y body 1 and has threaded connection there with. The annular portion 35 has a recess 3?.' to receive the upper end of the extension 8 of the insulator 7 and said insulator 36 is provided with a borelto permit the central electrode 17 to extend therethrou h and receive the usual terminal nut 38 W ich bears against the insulator 36and secures the head 18 in tight engagement with the bottom wall of the recess 16 of the insulator 7. By increasing and decreasing the number of washers 22 the position of the head 18 with res ect to the teeth 31 can be varied.

hilo I have Vshown and described the preferred embodiment ofmy invention, it will be understood that minor changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed a'vin'v thus described my invention, what l c ainlxr is 1. A spar plu coinprisin a bod', an insulator carried gy said bodygand prgjectig be ond the samefand havlng a recess in ts end, a central electrode carried by the .nsulator, a head formed on the central elec trede and located within the recess, a cap secured to said bodyiand overlying the end of the insulator and having an opening to expose the head, and a series of teeth carried by said cap andj spaced from the head.

insulator carried by said body iits en end of t 2. A spark plug comprising a body2 an and proJecting beyond the same and having a recess in a central electrode carried by the insulator, a head formed on the electrode and located within the recess and huvingjts upper face recessed to define an annular shoulder, said recess having a yroove in its bottom wall to receive the annu ar shoulder, a cap secured to said body and overlying the end ofthe insulator and having un o Jeninfr to expose the head, a series of teeth iormed about the inner; edge of the opening and spaced from the head.

3. A spark plug comprising a body, an insulator carried by said body and extending beyond the same, a central electrode carried by said insulator. said insulator having a recess in its end, a head formed on the electrode and located within the recess, a cap overlying the insulator, an extension formed on said cap and threaded to the bodybctween the same and the insulator, an annular flange formed on the inner edge vof the opening of said cap and being slotted to define teeth, said'teeth being spaced from the houd.

4. A spark plug comprising a body, an insulator carried by said body and projecting beyond said body at each cud thereof, an electrode carried by the insulator and projecting beyond the same at one end thereof, 9

a cap overlying one end of thc insulator and having an opening to expose the electrode und coperate with the same in forming a spurl: gap, and a second insulator secured to the body und receiving the other end of the lirst named insulator and having an opening to permit the electrode to extend throu h the same. i

5. i spark plug comprising a body, an insulator in said body and projecting beyond each end thereof, a second insulator of substantiall dome shape detachably secured to said body and have a recess to receive one lie first named insulator, a central electrode extending through said insulators, the first named insulator having a recess formed in one of its ends, a head formed on said electrode and located within said recess,` a cap detachably secured to said body and overlying the last named end of the first named insulator and having an openingto expose the head, and a series `of* annvularly arranged electrodes carried by said cap and spaced from the head.

In testimony whereof I allix my signature in presence of two witnesses.

HENRY SCHWETGER. .VVitnesseml OscAu KnUEGEu, W. G. Fisoxmn. 

